Field Station Modules(FSM)
Field Station Modules(FSM)
The Swagelok® field station module (FSM) transports a preconditioned, reduced-pressure process gas to an analyzer. Preconditioning a gas sample at the extraction point and transporting the sample at low pressure results in faster analyzer response time, less condensation, and less environmental impact. The FSM mounts directly to process nozzles and is highly configurable to match process conditions.
Faster Analyzer Response Time
In a high-pressure line with downstream flow control, gas molecules are more densely populated which creates slower flow velocity and longer purge times. Lowering the pressure of a gas sample means fewer molecules in the sample transport line and sample conditioning components; therefore, it is easier to flush the system, and the analyzer can respond faster to process changes. Typically, an FSM is used when process pressure is 3 bar (gauge) (43.5 psig) or higher.
Less Condensation
To avoid condensation in gas sampling, the FSM reduces the partial pressure of every gas in the sample mixture. One way to lower partial pressure of every gas is to reduce overall system pressure; the partial pressure of each gas drops in proportion to the overall pressure change. For example, if the absolute pressure of a sample is cut in half, the partial pressure of each gas in the mixture is cut in half as well, which results in half the water saturation in the sample. Using an FSM significantly reduces the chance of condensation forming in the sample transport line.
Improved Safety
If a system is compromised, the pressurized gas will expand to atmospheric pressure rapidly and can cause system damage or personal injury. The volumetric expansion ratio is directly proportional to the absolute pressure decrease. In high-pressure systems without field station modules, the expansion can be so great that the result is explosive in nature. Installing an FSM at the process sampling point means a smaller section of the sample system is exposed to high pressure, resulting in a safer overall environment.
